In Central America's sugarcane field, more and more workers are coming down with a disease that shuts down their kidneys. Researchers are struggling for a cause. Chemicals on the fields? Heat? Overwork? No one knows, but it's a leading cause of death for men in El Salvador and Nicaragua.

Across Central America, large numbers of men are dying from kidney disease. The cause is unknown, but a growing body of evidence suggests that hard manual labor -- especially in the region's sugarcane fields -- is partly to blame.

Across Central America, large numbers of men are dying from kidney disease. The cause is unknown, but a growing body of evidence suggests that hard manual labor -- especially in the region's sugarcane fields -- is partly to blame.

In Central America's sugarcane field, more and more workers are coming down with a disease that shuts down their kidneys. Researchers are struggling for a cause. Chemicals on the fields? Heat? Overwork? No one knows, but it's a leading cause of death for men in El Salvador and Nicaragua.